757 re-engined with GTF - 15% reduction in fuel burn (at least), be a great aircraft. On the other hand, Airbus could do the same with the A321 .
I think a new center section, wing box wing (CRFP), engines and engines on a stretched A320 ould produce a very potent 757/A310/767-200 replacement..
It could become a sub series with trans continental / trans atlantic capability combined with the wider A320 cabin & cargo container capability. Maybe up to 280 seats..
